Posted by chriscase on Sunday, September 24, 2006 at 5:41PM :
In Reply to: Re: Too lead or not to lead??? posted by Kaegi on Sunday, September 24, 2006 at 4:39PM :
All mine had inserts too. In fact, I believe that manufacturers started "induction hardening" valve seats in the 70's, rather than installing hard steel. Induction hardening is exposing the seats to radio waves (microwaves?) until they get red hot. I never thought blocks/heads were the best alloys for hardening. So, I think the current "hardened seats" in iron heads are not as good as ours were OE.
I was a mechanic in the late 70's, and had my doubts about the whole "unleaded beats seats" idea. Sure, valves burnt, but the engines were 100,000 old when they did. And, some flat heads had Stellite valves in them already, nothing harder than that, and that was long before unleaded.
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